The present invention relates to a semiconductor device and a manufacturing method thereof, and in particular, to flip-chip mounting for a semiconductor device in which electrode pads are arranged at a narrow pitch.
With the spread of small and high-performance electronic apparatuses, a semiconductor packaging technique in the apparatuses has recently become important, which creates a big challenge improving a technique for coupling a semiconductor chip and a mounting board.
As one of the techniques for dealing with an increase in the number of coupling terminals and a narrow pitch between electrode pads, those having been brought by high integration of semiconductor chips, a flip-chip mounting technique using a Cu pillar is under development.
In a Cu pillar, a pillar made of Cu is formed, by using a plating process, over a terminal pad of a semiconductor chip in order to be coupled to a mounting board, and hence the Cu pillar can deal with a narrow pitch, and can deal with a larger current because Cu is used as a material, in comparison with Au or solder.
As a related art of the field of the technology, a technique as disclosed in Patent Document 1 can be cited. Patent Document 1 discloses “A semiconductor device in which a ratio of the diameter (top diameter) of a portion of a solder bump, the portion being farthest from a semiconductor substrate, to the diameter (bottom diameter) of the bottom of the solder bump is 1:1 to 1:4.”
Further, Patent Document 2 discloses “A coupling terminal of a semiconductor device having a shape in which the cross-sectional area of a first cross section, the cross section being parallel to the surface of a protective film at an end portion contacting a solder terminal, is larger than the cross-sectional area of a second cross section located in the same plane as the surface of the protective film.”
Furthermore, Patent Document 3 discloses “A semiconductor chip in which the angle between the upper end surface of a pillar part and a side surface contacting the upper end surface is an acute angle.”